Korea mobile plans for foreigners: prepaid vs postpaid, MVNO savings explained, eSIM options and limits

Korea Mobile Plans for Long-Stay Foreigners (2025 Edition)

Who should read this

• You plan to stay 90+ days and will apply for a Residence/Alien Registration Card (ARC). Korean authorities require ARC registration for stays over 90 days. Apply within 90 days of arrival. (외교부 해외공관)

• You need to understand prepaid vs. postpaid, MVNO (알뜰폰), and eSIM choices, including how throttling and number portability work.

1) Quick decision path (5 steps)

1. First 0–14 days in Korea: Use a prepaid airport eSIM/SIM for instant data. KT and LG U+ sell tourist eSIMs online and at airports. ([roaming.kt.com][2])

2. Within 90 days: Apply for your ARC. You need it for most postpaid plans and identity-linked services. (외교부 해외공관)

3. After ARC arrives: Decide postpaid with a major carrier (SKT/KT/LG U+) or MVNO (알뜰폰) for lower monthly cost. ([Omdia][3])

4. If you already have a Korean number: Use mobile number portability (번호이동) to keep your number when switching. ([모바일 번호 이동성][4])

5. Before you sign: Check throttling rules, contract length, and any penalties for early termination. (Carrier/MVNO pages list speed caps and terms.) ([roaming.kt.com][2])

2) Network landscape (why coverage rarely fails—and who leads)

• All three MNOs—SK Telecom (SKT), KT, LG U+—run nationwide 5G/LTE networks with excellent urban coverage. Independent testing shows SKT often leads in overall experience, while KT has strong 5G availability; LG U+ is competitive on speeds. ([OpenSignal][5])

• Korea’s 5G speeds kept rising in 2024; official figures reported ~9.2% year-on-year improvement in 2024, with operator averages around 956–1,065 Mbps on government tests. ([RCR Wireless News][6])

3) Prepaid vs. postpaid for long-stays

• Prepaid: Easy start; good for your first month. Some tourist eSIMs are data-only and cannot be extended once deleted; check each product’s extension/top-up rules. ([roaming.kt.com][2])

• Postpaid: Better value for heavy data and unlimited calls. Requires ARC and typically a Korean payment method. (외교부 해외공관)

4) MVNO (알뜰폰): how to save 20–50% monthly

• Speed after cap: “Unlimited” often means daily high-speed data cap (e.g., 3GB/day) then throttled speeds (commonly 1–5 Mbps). LG U+ describes a 5 Mbps post-cap on some unlimited eSIMs. ([LG U+][8])

• Contract length: Many MVNOs offer month-to-month or short minimum terms versus 12–24 months at MNOs. [Unverified—varies by MVNO; check the specific contract page.]

• Sign-up: Foreigners can generally register with passport (prepaid) or ARC (postpaid). Many MVNOs provide English support. ([우림모바일][9])

5) eSIM pricing snapshots (tourist-style data plans you can start with today)

KT eSIM (Data-only) — online vs. counter (as listed by KT Roaming, data-only)

LG U+ eSIM (Data-only; shows throttling model)

• “Unlimited” means daily high-speed bucket (e.g., 3GB/day), then 5 Mbps for the rest of the day. Site advertises nationwide 5G/LTE. Prices vary by validity (e.g., 1 day ₩6,500; multi-day bundles). ([LG U+][8]) Sources: LG U+ eSIM product page. ([LG U+][8])

LG U+ SIM (Data + Voice)

• Offers 010 Korean number with unlimited data (policy dependent) and airport pickup; details and add-on voice top-ups shown on the official product page. ([LG U+][10]) Sources: LG U+ SIM (Data+Voice) page. ([LG U+][10])

Note on SKT tourist eSIMs: SKT’s official, English pricing and throttle policy pages are harder to reference publicly. Some resellers advertise SKT unlimited at up to ~100 Mbps after cap, but those claims come from resellers, not SKT’s own site. Treat as [Unverified] unless you see the rule on an SKT-controlled domain. ([코리아심카드][11])

6) Keeping your number (번호이동, MNP)

• You can usually keep your number when switching carriers/MVNOs in Korea using MNP. Your new provider initiates the port with your consent and ID. (Exact forms and steps vary by provider.) ([모바일 번호 이동성][4])

• Enterprise documentation and integrator guides confirm Korea requires multiple forms and regulatory checks for number porting; consumer processes are simpler because the carrier handles it. ([AWS Documentation][12])

7) Throttling & “unlimited” fine print (read this before you buy)

• Daily cap model: Many “unlimited” plans give X GB/day at full speed, then throttle for the rest of the day. LG U+ shows 5 Mbps after the daily bucket on its eSIM page. ([LG U+][8])

• Data-only eSIMs: KT’s data eSIM does not support personal authentication (often required by banking or ID services), and deleting the profile ends the plan. ([roaming.kt.com][2])

• Extension/top-ups: KT lists clear extension rules by product; do not assume you can add voice to a data-only eSIM. ([roaming.kt.com][2])

8) Example setups (realistic, action-ready)

Case A — International student (D-2), dorm in Seoul, heavy data

• Month 0: Buy KT eSIM 30-day online (₩64,300) to cover orientation and settling. ([roaming.kt.com][2])

• Within 90 days: Apply for ARC. (외교부 해외공관)

• After ARC: Compare MVNO postpaid vs MNO student plans. If your usage is >20GB/month, an MVNO plan with daily buckets could be cheaper than MNO. [Unverified—price levels vary monthly.]

• If switching later: Use MNP to keep the same number. ([모바일 번호 이동성][4])

Case B — Working professional (E-7), lives in Gyeonggi, needs voice + verification

• Arrival: LG U+ Data + Voice SIM for instant 010 number and data while house-hunting. ([LG U+][10])

• After ARC: Move to postpaid on SKT/KT/LG U+ or MVNO with voice. Confirm throttling and contract length. ([LG U+][8])

• Banking and apps: Avoid data-only eSIMs if you need personal authentication frequently. ([roaming.kt.com][2])

9) Cost & requirements tables (for fast comparison)

A. What documents do you need?

B. Tourist-style eSIM prices (useful for your first month)

USD note: To convert quickly, assume ₩1,300 ≈ USD 1. Mark conversions as rough.

10) Do / Don’t checklist

• Apply for your ARC within 90 days if staying long-term. (외교부 해외공관)

• Start with a tourist eSIM/SIM while you wait for ARC. ([roaming.kt.com][2])

• Read the throttling section of any “unlimited” plan. ([LG U+][8])

• Use MNP to keep your number when switching to MVNO or between carriers. ([모바일 번호 이동성][4])

• Don’t delete your KT eSIM profile expecting to “extend” it later; you’ll need a new purchase. ([roaming.kt.com][2])

• Don’t pick data-only if you need identity verification (banking, government logins). KT states data-only eSIM does not support personal authentication. ([roaming.kt.com][2])

• Don’t assume prepaid is always cheapest for long-stay heavy users; validate current MVNO deals. [Unverified—depends on current promotions.]

11) Common pitfalls (with fixes)

• “My unlimited slowed down.” You hit the daily cap; you are now at 1–5 Mbps (varies by plan). Confirm the plan’s post-cap speed and consider a higher tier or MVNO with a larger daily bucket. ([LG U+][8])

• “Bank app fails on eSIM.” Some data-only eSIMs cannot pass personal authentication. Use a plan with voice/SMS and proper ID linkage, or switch after you get your ARC. ([roaming.kt.com][2])

• “I moved to the suburbs and signal dropped.” In rural edges, performance varies. Check Opensignal insights and carrier maps; you may prefer SKT for broader coverage, or KT for 5G availability in certain zones. ([OpenSignal][5])

12) FAQ (date-stamped answers)

13) Glossary (telecom + Korea living terms)

• ARC (Alien/Residence Registration Card): Mandatory ID for stays >90 days; needed for many services, including most postpaid mobile plans. (외교부 해외공관)

• MVNO (알뜰폰): Discount carrier using MNO networks (SKT/KT/LG U+). Policies vary; read throttling rules. ([Omdia][3])

• MNP (번호이동): Mobile Number Portability; keep your number when switching. ([모바일 번호 이동성][4])

• Personal authentication (본인인증): Korean identity verification for apps/sites; not supported on some data-only eSIMs. ([roaming.kt.com][2])

• Jeonse / Banjeonse / Management fee: Housing deposit systems and monthly building fees. Not telecom topics, but these terms appear in onboarding; your address proof may be needed for postpaid.

FOHO: Secure Your Address, Simplify Everything Else

• Excellent support: Real help from search to move-in, plus prompt follow-ups when you need them.

• Seamless landlord communication: Message owners in one place—before and after move-in—so nothing gets lost.

• Fast, secure payments: Pay deposits and rent with a streamlined, receipt-backed flow.

• Wide listing coverage: Options across major neighborhoods and budgets, so you can choose what truly fits.

Source list (by section)

• eSIM/SIM pricing & rules: KT Roaming eSIM and SIM pages; LG U+ eSIM and SIM pages. ([roaming.kt.com][2])

• ARC requirement: Republic of Korea Ministry of Foreign Affairs (overseas missions); university and city guidance reiterating the 90-day rule. (외교부 해외공관)

• Network performance: Opensignal South Korea reports (2024), government-reported speed improvements (2024→2025). ([OpenSignal][5])

• MVNO policy context: Industry commentary on government wholesale price reductions to aid MVNOs. ([juniperresearch.com][7])

• Number portability: MNP overview for Korea; enterprise porting guidance indicating paperwork complexity handled by providers for consumers. ([모바일 번호 이동성][4])